A number of lighting control systems have been developed that sense the amount of daylight in a room or building (a “controlled space”) and automatically adjust the lumen output of lights installed, typically fluorescent lights, in that controlled space to save money on energy expenses. U.S. Pat. No. 7,190,126 (“Paton”) provides an example of a daylight control system, which utilizes a controller, programmed through a portable commissioning system that includes a light sensor, to control a plurality of ballasts, each controlling one or more lights in the controlled space. Aside from the impracticality of relying on a portable light sensor to read daylight levels in the controlled space, the Paton system is also limited by the manner in which the controller communicates with the ballasts.
Each ballast sends and receives large amounts of data. For example, a ballast will send data about its status (its operating condition), how bright the lights are that it is controlling, and its power consumption, while receiving data about how bright the lights should be, whether they should be on or off, etc. See U.S. Pat. No. 5,530,322 for an example of a multi-zone lighting controller system. When a large number of ballasts are being controlled, the amount of data becomes enormous and overwhelms the controller, or at least significantly slows the operation of the system, thereby inhibiting the efficiency of the system and its ability to save money by controlling the amount of light being used at any given point in time.
As noted above, the use of a portable light sensor is impractical because light levels within a controlled space with windows or skylights change constantly as a day goes by and someone cannot be economically employed to walk around all day testing light levels. Daylight levels in the morning are very different from mid-day and evening levels. Likewise, atmospheric conditions, such as clouds passing before the sun, can cause short to long-term changes in the amount of available daylight. To have a truly cost-effective solution, daylight levels must be constantly measured and the lights adjusted accordingly. Moreover, it is not enough to just control the lights in a room, especially one with many windows or skylights, because sometimes too much daylight will be let in. Accordingly, it is desirable to control powered window coverings to increase or decrease natural daylight in addition to controlling the level of artificial light in a controlled space.
In addition to measuring light, it is desirable to measure motion within the controlled space so that a space will not be unnecessarily illuminated. For example, many controlled spaces, such as a warehouse, a gym or a room within an office, do not need to be illuminated (or fully illuminated) when no one is in that space. As much as forty to fifty percent of energy consumption in the commercial sector is attributable to lighting, second only to heating and air conditioning. Lighting and HVAC automation would therefore help to decrease energy use and reduce costs.
Motion detectors integrated with a timing device, referred to herein as an occupancy sensor, have been used to control lighting within a controlled space. See U.S. Pat. No. 5,489,827 for an example of a light controller with an occupancy sensor. A primary disadvantage of such occupancy sensors is that they often incorrectly turn on the lighting system, referred to as a false on or nuisance on. While dual technology occupancy sensors (which use both a passive infrared sensor and an ultrasonic sensor) help to prevent false ons, they can still be falsely activated by HVAC systems. To overcome the HVAC limitation, the security industry has used triple technology occupancy sensors (with microwave sensors as the third type of sensor) to help reduce false alarms. U.S. Pat. No. 4,401,976 illustrates a multiple sensor sec system. While triple technology sensors have not typically been used in the lighting/building control industry, U.S. Pat. No. 5,986,357 does illustrate the use of a triple technology occupancy sensor for a variety of applications, including lighting control. Unfortunately, the triple technology sensors available on the market are not easily adapted for use in lighting/building control systems. A solution is needed to universally adapt any type of motion sensor into a lighting/building control system.
Furthermore, while lighting control systems are typically installed in a controlled space by an electrical contractor, security systems are typically installed by a security system contractor, and HVAC systems are typically installed by an HVAC contractor. As a result, each controlled space ends up being equipped with three different control systems and three different control panels for controlling lighting, security and HVAC. A solution is needed that allows a single system to control lighting and to provide common control signals to security, HVAC and other automated systems within a controlled space.